By disabling some of the cylinders on an engine when the desired torque is relatively low (e.g., at idle or other situations), an engine can be operated at a higher manifold pressure to supply needed airflow to the operating cylinders. For example, the engine may be operated with a wider throttle while cylinders are disabled. This can reduce engine pumping losses and make the engine more efficient.
However, when an engine is run on less than all of its cylinders, the frequency of torque pulsations and the magnitude of those pulsations may be increased relative to operating the engine with all cylinders enabled. The low frequency and high magnitude torque pulsations can result in transmission of more vibration to vehicle occupants. Vehicle occupants may thus be more likely to perceive an undesirable amount of noise, vibration, harshness (NVH) during operating modes when cylinders are disabled.
In one approach, the above issue may be addressed by a method of operating an internal combustion engine, comprising:
disabling a first piston cylinder of the engine;
positioning a turbulence member in a first position while the first piston cylinder is disabled, the turbulence member being movably disposed in an air intake pathway between a throttle of the engine and an intake valve of an enabled piston cylinder; and
positioning the turbulence member in a second position while the first piston cylinder is disabled, where moving the turbulence member from the first position to the second position causes turbulence to vary in the air intake pathway.
In this way, it is possible to adjust combustion characteristics to at least partially compensate for potentially increased noise and/or vibration during partial cylinder operation, such as during lower torque and/or lower speed conditions.